Oral delta9-tetrahydrocannabinol toxicity in rats treated for periods up to six months

The Relevance of Sex in the Association of Synthetic Cannabinoid Use With Psychosis and Agitation in an Inpatient Population

BACKGROUND

Current evidence suggests that women are more sensitive to the effects of cannabinoids. The aim of this study was to investigate the relevance of sex in the association of synthetic cannabinoid (SC) use with psychosis and agitation.

METHODS

A retrospective chart review was conducted for patients admitted to a psychiatric unit (2014-2016) to extract information on demographic factors, use of substances, clinical symptoms, and pharmacologic treatments. Study groups were defined as SC users (anyone who reported use of SCs over the past 3 months), cannabis users (positive toxicology screen for Δ⁹-tetrahydrocannabinol [THC]), and controls (those who denied use of SCs over the past 3 months and had negative toxicology for THC).

RESULTS

Digital charts of 983 patients were reviewed. A total of 162 subjects reported use of SCs over the past 3 months (76% male), and 292 subjects had positive toxicology screen for THC (67% male). A total of 38.9% of SC users (n = 63) had positive urine toxicology screen for THC. SC users had higher risks of psychotic presentations (adjusted odds ratio [AOR] = 3.390; 95% CI, 1.390-8.267) and agitation (AOR = 4.643; 95% CI, 1.974-10.918) compared to the controls. While women had lower rates of psychosis than men in the cannabis and control groups, the rates were markedly potentiated with SC use to high levels (79%) approximately equal to that seen in men (80%). There was also a significant interaction between SC use and sex for agitation (AOR = 0.308; 95% CI, 0.117-0.808). Female SC users were significantly more agitated than male SC users (73.7% vs 47.6%, respectively, P = .005).

CONCLUSIONS

SC users are more likely than nonusers to be psychotic or agitated in an inpatient setting. The potentiated rates of psychosis and agitation with SC use in women suggest that they may have a greater sensitivity to these synthetic compounds.​.

Early Cannabinoid Exposure as a Source of Vulnerability to Opiate Addiction: A Model in Laboratory Rodents

Recent findings have identified an endogenous brain system mediating the actions of cannabis sativa preparations. This system includes the brain cannabinoid receptor (CB-1) and its endogenous ligands anandamide and 2-arachidonoyl-glycerol. The endogenous cannabinoid system is not only present in the adult brain, but is also active at early stages of brain development. Studies developed at our laboratory have revealed that maternal exposure to psychoactive cannabinoid results in neuro-developmental alterations. A model is proposed in which early Δ9-tetrahydrocannabinol (THC) exposure during critical developmental periods results in permanent alterations in brain function by either the stimulation of CB-1 receptors present during the development, or by the alterations in maternal glucocorticoid secretion. Those alterations will be revealed in adulthood after challenges either with drugs (i.e. opiates) or with environmental stressors (i.e. novelty). They will include a modified pattern of neuro-chemical, endocrine, and behavioral responses that might lead ultimately to inadaptation and vulnerability to opiate abuse.

Alcohol, drugs, caffeine, tobacco, and environmental contaminant exposure: reproductive health consequences and clinical implications

Reproductive function and fertility are thought to be compromised by behaviors such as cigarette smoking, substance abuse, and alcohol consumption; however, the strength of these associations are uncertain. Furthermore, the reproductive system is thought to be under attack from exposure to environmental contaminants, particularly those chemicals shown to affect endocrine homeostasis. The relationship between exposure to environmental contaminants and adverse effects on human reproductive health are frequently debated in the scientific literature and these controversies have spread into the lay press drawing increased public and regulatory attention. Therefore, the objective of the present review was to critically evaluate the literature concerning the relationship between lifestyle exposures and adverse effects on fertility as well as examining the evidence for a role of environmental contaminants in the purported decline of semen quality and the pathophysiology of subfertility, polycystic ovarian syndrome, and endometriosis. The authors conclude that whereas cigarette smoking is strongly associated with adverse reproductive outcomes, high-level exposures to other lifestyle factors are only weakly linked with negative fertility impacts. Finally, there is no compelling evidence that environmental contaminants, at concentrations representative of the levels measured in contemporary biomonitoring studies, have any effect, positive or negative, on reproductive health in the general population. Further research using prospective study designs with robust sample sizes are needed to evaluate testable hypotheses that address the relationship between exposure and adverse reproductive health effects.

Perinatal exposure to delta 9-tetrahydrocannabinol increases presynaptic dopamine D2 receptor sensitivity: a behavioral study in rats

The endogenous cannabinoid system is a relevant modulator of dopaminergic synapses in dorsal striatum. Perinatal exposure to cannabinoid receptor agonists has been described to affect the development of dopaminergic circuits in rat brain. The epigenetic alterations described affected both dopamine neurons and dopamine receptor-expressing neurons. The present work has been designed to explore the effects of maternal exposure to orally delivered Delta(9)-tetrahydrocannabinol, (Delta(9)-THC 0.1, 0.5, 2 mg/kg) on the behavioural responses to the dopamine receptor agonists apomorphine (0.1 mg/kg) and quinpirole (0.5 mg/kg), at doses that target presynaptic dopamine D2 receptors. Maternal exposure to Delta(9)-THC affected both the developmental pattern of motor behaviours, and the behavioural responses to acute injections of apomorphine and quinpirole, tested in an open field. The effects were sex dimorphic, being more intense in male animals. Perinatal exposure to Delta(9)-THC resulted in enhanced presynaptic dopamine D2 receptor mediated responses such as immobility and inhibition of locomotion. Additionally, postsynaptic dopamine D2 receptor agonist-induced stereotypes were reduced in the group exposed to the highest dose of Delta(9)-THC (2 mg/kg). However, the late-onset pattern of behavioural activation observed after acute quinpirole exposure was equal in vehicle- and cannabinoid-treated animals. These effects suggest that perinatal exposure to Delta(9)-THC affects the functionality of dopaminergic autoreceptors, inducing a greater sensitivity to the presynaptic actions of dopamine D(2) receptor agonists.

Cannabinoid transmission and reward-related events

The reward/reinforcement circuitry of the mammalian brain consists of synaptically interconnected neurons associated with the medial forebrain bundle, linking the ventral tegmental area, nucleus accumbens, and ventral pallidum. Electrical stimulation of this circuit supports intense self-stimulation in animals and, in humans, produces intense pleasure or euphoria. This circuit is strongly implicated in the neural substrates of drug addiction and in such addiction-related phenomena as withdrawal dysphoria and craving. This circuit is also implicated in the pleasures produced by natural rewards (e.g., food, sex). Cannabinoids are euphorigenic in humans and have addictive liability in vulnerable persons, but were long considered "anomalous" drugs of abuse, lacking pharmacological interaction with these brain reward substrates. It is now clear, however, that cannabinoids activate these brain substrates and influence reward-related behaviors. From these actions, presumably, derive both the abuse potential of cannabinoids and the possible clinical efficacy in dysphoric states.

Marijuana's interaction with brain reward systems: update 1991

The most pervasive commonality amongst noncannabinoid drugs of abuse is that they enhance electrical brain stimulation reward and act as direct or indirect dopamine agonists in the reward relevant dopaminergic projections of the medial forebrain bundle (MFB). These dopaminergic projections constitute a crucial drug sensitive link in the brain's reward circuitry, and abused drugs derive significant abuse liability from enhancing these circuits. Marijuana and other cannabinoids were long considered "anomalous" drugs of abuse, lacking pharmacological interaction with these brain reward substrates. It is now clear, however, that delta 9-tetrahydrocannabinol (delta 9-THC), marijuana's principal psychoactive constituent, acts on these brain reward substrates in strikingly similar fashion to noncannabinoid drugs of abuse. Specifically, delta 9-THC enhances MFB electrical brain stimulation reward, and enhances both basal and stimulated dopamine release in reward relevant MFB projection loci. Furthermore, delta 9-THC's actions on these mechanisms is naloxone blockable, and delta 9-THC modulates brain mu and delta opioid receptors. This paper reviews these data, suggests that marijuana's interaction with brain reward systems is fundamentally similar to that of other abused drugs, and proposes a specific neural model of that interaction.

delta 9-Tetrahydrocannabinol antagonism of the anterior pituitary response to estradiol in immature female rats

The potential estrogenicity or antiestrogenicity of delta 9-tetrahydrocannabinol (THC), the chief psychoactive constituent of marijuana, was evaluated in immature female rats treated for 3 days with estradiol (E2; 1 microgram/kg), THC (10 mg/kg body weight), or E2 + THC. Estradiol treatment significantly increased anterior pituitary, uterine, and oviduct weights. When THC was administered with E2, it prevented the E2-induced increase in pituitary weight, but had no effect on either the uterine or oviduct weight response to E2. In the E2 treatment group, basal prolactin levels were increased and a prolactin surge occurred on the afternoon of the 26th day of age. However, E2-stimulated basal and surge levels of prolactin were significantly attenuated by concomitant THC treatment. Moreover, pituitary prolactin concentrations, which were elevated in E2-treated rats, did not differ from control values in E2 + THC-treated animals. The E2-induced decrease in dopamine turnover rates in the medial basal hypothalamus and increase in the number of anterior pituitary dopamine D2-binding sites (Bmax) were not affected by concomitant THC treatment. Thus, THC antagonizes E2 action on the anterior pituitary via yet to be elucidated mechanism(s).

Delta 9-tetrahydrocannabinol enhances presynaptic dopamine efflux in medial prefrontal cortex

Acute administration of 1.0-2.0 mg/kg delta 9-tetrahydrocannabinol (delta 9-THC) increased presynaptic dopamine (DA) efflux in the medial prefrontal cortex of rats, as measured by intracerebral microdialysis in awake, behaving rats. These data are congruent with suggestions that (1) marijuana's euphorigenic effects and abuse potential may be related to augmentation of presynaptic DA mechanisms, and (2) the medial prefrontal cortex may be an important site of action for drugs of abuse in general and for delta 9-THC in particular.

Delta 9-tetrahydrocannabinol produces naloxone-blockable enhancement of presynaptic basal dopamine efflux in nucleus accumbens of conscious, freely-moving rats as measured by intracerebral microdialysis

This study examined the effects of acute administration of delta-9-tetrahydrocannabinol (delta 9-THC), the psychoactive ingredient in marijuana, on extracellular efflux of dopamine (DA) and its metabolites as measured by in vivo microdialysis in nucleus accumbens of conscious, freely-moving rats. delta 9-THC, at low doses (0.5-1.0 mg/kg), which significantly enhance brain stimulation reward (intracranial self-stimulation), significantly increased DA efflux in nucleus accumbens. Augmentation of DA efflux by delta 9-THC was abolished by removal of calcium (Ca++) ions from the perfusion fluid, indicating a Ca(++)-dependence of delta 9-THC's action. Augmentation of DA efflux by delta 9-THC was either totally blocked or significantly attenuated by doses of naloxone as low as 0.1 mg/kg. Given the postulated role of mesocorticolimbic DA circuits in mediating and/or modulating brain stimulation reward, the present data raise the possibility that marijuana's rewarding effects, and hence its euphorigenic effects and abuse potential, may be related to pharmacological augmentation of presynaptic DA mechanisms. Additionally, the DA mechanisms enhanced by marijuana appear to be modulated by an endogenous opioid peptide system.

The effects of delta 9-tetrahydrocannabinol on potassium-evoked release of dopamine in the rat caudate nucleus: an in vivo electrochemical and in vivo microdialysis study

The effect of systemically administered delta 9-tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, on the potassium-evoked release of dopamine (DA) was examined in the neostriatum of the chloral hydrate anesthetized rat. Both in vivo electrochemical and in vivo microdialysis techniques were employed. A low dose of THC (0.5 mg/kg, i.p.) increased the time course of potassium-evoked in vivo electrochemical signals corresponding to released extracellular DA. In vivo microdialysis showed an increase in potassium-evoked DA release following 0.5 and 2.0 mg/kg doses of THC. Potassium-evoked electrochemical signals corresponding to released extracellular DA were augmented in time course following i.p. administration (5.0 mg/kg) of nomifensine, a recognized and potent catecholaminergic reuptake blocker. In addition, in vivo brain microdialysis studies of nomifensine (5.0 mg/kg i.p.) on neostriatal potassium-evoked DA release showed that DA levels were augmented in magnitude over the time course of the microdialysis. Taken together, these studies indicate that THC has a potent presynaptic augmenting effect on at least the neostriatal portions of the mesotelencephalic DA system in the rat, although the possibility that this effect could be mediated transsynaptically cannot be ruled out. Given the previous extensive evidence for an involvement of portions of the mesotelencephalic DA system in mediating the reinforcing and euphorigenic properties of many classes of abused drugs, and in mediating direct electrical brain stimulation reward, we suggest that the presently demonstrated effects of THC on forebrain dopamine function may be related to marijuana's euphorigenic properties and, thus, to its abuse potential.

Quantitative changes in hippocampal structure following long-term exposure to delta 9-tetrahydrocannabinol: possible mediation by glucocorticoid systems

Although cannabinoids exert strong effects on brain function, there have been no extensive analyses of the long-term effects of cannabinoids on mammalian brain structure. Consequently, we conducted quantitative light and electron microscopic studies on the brains of rats treated chronically with delta 9-tetrahydrocannabinol (THC) (5 X weekly for 8 months--approximately 30% of the life-span). In these studies, we found significant THC-induced changes in hippocampal structure: specifically, THC-treated animals exhibited decreased neuronal density and increased glial cell reactivity (i.e. an increase of cytoplasmic inclusions). In addition, we confirmed prior reports of THC-induced increases in adrenal-pituitary activity, since both adrenocorticotropic hormone (ACTH) and corticosterone were elevated substantially during an acute stress. However, the animals appeared to be only minimally affected behaviorally by the doses used (highest dose: 8 mg/kg) and no effects of THC were observed on several ultrastructural variables, including synaptic density. The observed hippocampal morphometric effects of chronic THC are similar to apparent glucocorticoid-dependent changes that previously have been found to develop in rat hippocampus during normal aging. Given that cannabinoids and steroids are similar in chemical structure in several respects, therefore, the present results seem to raise the possibility that chronic THC exposure may alter hippocampal anatomical structure by interactions with, or mimicry of, adrenal steroid activity.

Facilitation of brain stimulation reward by delta 9-tetrahydrocannabinol

The present experiment explored whether delta 9-tetrahydrocannabinol (delta 9-THC), the psychoactive ingredient in marijuana, shares with other drugs of abuse the ability to facilitate brain stimulation reward acutely, as measured by electrical intracranial self-stimulation (ICSS). Laboratory rats were implanted with stimulation electrodes in the medial forebrain bundle, and trained to stable performance on a self-titrating threshold ICSS paradigm. delta 9-THC, at a dose believed pharmacologically relevant to moderate human use of marijuana, acutely lowered ICSS thresholds, suggesting that marijuana acts on similar CNS hedonic systems to most other drugs of abuse.

Behavioral effects of THC as a function of environment and prior drug experience

Holtzman albino rats were divided into 4 groups, and on 5 consecutive days each group was exposed to one of 4 conditions. The drug-adapted group was given delta-9-tetrahydrocannabinol (THC) (0.0, 0.5, 2.5 or 5.0 mg/kg PO) in their home cages, while the environment-adapted group was given vehicle and placed for one hr in the chamber where they were later tested. The naive group was given vehicle in their home cages and the drug + environment adapted group was given THC and placed in the test chamber. One week later, all rats were given either 0.0, 0.5, 2.5, or 5.0 mg/kg THC and placed in the test chamber where standing, sitting, and behavioral activity were measured. The results showed that the behavioral effects of THC are a function of environmental familiarity in rats who are drug naive but not in rats given prior exposure to THC.

A randomised multicentre single blind comparison of a cannabinoid anti-emetic (levonantradol) with chlorpromazine in patients receiving their first cytotoxic chemotherapy

One hundred and eight patients selected to receive combinations of highly emetic cytotoxic chemotherapy for malignant disease were included in a study of anti-emetic therapy. The patients were randomly allocated to receive levonantradol (0.5, 0.75 or 1 mg) or chlorpromazine (25 mg) prior to receiving their first course of cytotoxic therapy. The appropriate anti-emetic was administered 2 hr prior to the start of chemotherapy, 2 hr after chemotherapy and subsequently at 4-hourly intervals for a further 8 hr. The extent of anorexia, nausea and vomiting along with other side-effects were assessed at regular intervals by physicians and nursing staff during the 24 hr following chemotherapy. In addition, a self-assessment questionnaire was completed by the patients. Levonantradol (0.5 mg) was superior to chlorpromazine (25 mg) as an anti-emetic. Both were reasonably well tolerated, although at this dose of levonantradol 22% of patients experienced dysphoric reactions. At higher doses of levonantradol the proportion of patients experiencing these reactions rose to 50%, but without a concomitant increase in antiemetic activity. Neither drug achieved satisfactory control of vomiting in patients receiving combinations containing cis-platinum. We conclude that levonantradol (0.5 mg) is a more effective anti-emetic than chlorpromazine (25 mg) in patients receiving cytotoxic chemotherapy. However, its use cannot be recommended due to its high incidence of unacceptable central nervous system side-effects.

Learning impairment in the radial-arm maze following prolonged cannabis treatment in rats

Chronic oral administration of cannabis extract to rats (daily delta 9-tetrahydrocannabinol dose 20 mg/kg) was examined in three experiments for its residual effect on radial-arm maze learning following a 1-month drug-free period. Learning a simple eight-arm maze was significantly impaired in rats treated for either 6 months (Experiment I) or 3 months (Experiment II) with the drug. In Experiment III, animals that received the extract for 3 months exhibited significant learning deficits on a much more difficult 12-arm radial maze. The results demonstrate that the deleterious effects of cannabis on radial-arm maze learning are probably due to a tendency toward increased vigilance and perseveration, possibly combined with an impaired utilization of spatial cues.

Marihuana and sex: a critical survey

Marihuana usage is associated with a life-style that involves earlier and more frequent sexual activity. Marihuana usage does not affect human male testosterone levels significantly, but does adversely affect sperm production. Animal studies have not found consistent changes in weights of male sexual organs but have corroborated the adverse effects of cannabinoid compounds on sperm production. The biological significances of these effects on sperm production are unclear, however, since there is no evidence that human marihuana users or male animals given cannabinoid compounds are less fertile or are at risk for dominant lethal mutations. Cannabinoid compounds reliably inhibit ovulation in animals and are associated with depressed luteinizing hormone (LH) levels in both female and male animals. The decreased LH levels appear to be due to both hypothalamic and ovarian sites of action. Treatment with cannabinoid compounds is also associated with lower testosterone levels in male and lower prolactin levels in female animals. Effects on progesterone levels are inconclusive. Cannabinoid compounds do not possess estrogenic activity. Despite some consistencies in the data in virtually every study conducted with animals, there has been a basic confounding between direct drug action and secondary effects resulting from drug-induced decreases in food and water consumption and attendant weight loss. Almost all of the adverse effects of cannabinoid exposure on reproductive organs can be attributed to these secondary effects.

Superiority of nabilone over prochlorperazine as an antiemetic in patients receiving cancer chemotherapy

Two double-blind, crossover trials comparing the antiemetic effectiveness of nabilone, a new synthetic cannabinoid, with that of prochlorperazine were conducted in patients with severe nausea and vomiting associated with anticancer chemotherapy. Of 113 patients evaluated, 90 (80 per cent) responded to nabilone therapy, whereas only 36 (32 per cent) responded to prochlorperazine (P less than 0.001). Complete relief of symptoms was infrequent, occurring only in nine patients (8 per cent) given nabilone. When both drugs were compared, both nausea (P less than 0.01) and vomiting episodes (P less than 0.001) were significantly lower in patients given nabilone. Moreover, patients clearly favored nabilone for continued use (P less than 0.001). Predominant side effects noted by patients were similar for both agents and included somnolence, dry mouth and dizziness but were about twice as frequent and more often severe in patients receiving nabilone. In addition, four patients (3 per cent) taking nabilone had side effects (hallucinations in three, hypotension in one) that required medical attention. Euphoria associated with nabilone was infrequent (16 per cent) and mild.

Teratologic evaluation of delta9-tetrahydrocannabinol in mice, including a review of the literature

Pregnant CD1 mice received 5, 15, 50, 150 mg/kg/day of delta9-THC in sesame oil on days 6-15 of gestation orally by gavage and were killed about one day before expected delivery. Treatment had no effect on the maternal weight gain, prenatal mortality rate, fetal weight, and the frequency of gross external, internal, and skeletal abnormalities.